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염한길,박성제,홍용주,고준석,인세환,김효봉,Yeom, Hankil,Park, Seoung-Je,Hong, Hong-Ju,Ko, Junseok,In, Sehwan,Kim, Hyo-Bong 대한기계학회 2015 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.3 No.4
국내 사용되고 있는 적외선 검출기 냉각용 스털링 극저온 냉동기는 상당부분 수입에 의존하고 있으며, 높은 대당 가격, 제한적인 수명 및 내구성 부족으로 지속적인 극저온 냉동기 수요가 발생하고 있다. 그런데 적외선 검출기용 극저온 냉동기 기술은 국방, 우주관련 기술로 선진국의 기술이전이나 공동 개발이 매우 제한적이다. 본 연구를 통해 개발하고자 하는 맥동관 극저온 냉동기는 저온구동부의 기계적 피스톤을 가스피스톤으로 대체하고, 압축방식을 선형압축방식으로 바꿈으로써 낮은 진동, 높은 수명 및 내구성을 확보할 수 있다. 이를 통해 맥동관 냉동기의 기술수준을 선진국에 근접시키고, 독자적인 냉각형 적외선 검출기 설계 및 제작기술에 대한 기술을 확보하고자 한다. Most of the Stirling cryocoolers used for infrared detector cooling in domestic is imported. Because the cooler has a high price, short life and poor durability, demand for the coolers continues steadily. However, the cooler is highly related to defense and space technology, technology transfer or co-development with the countries having experties in cooler design is very limited. The pulse tube cooler to be developed in this study is such that the mechanical piston in low temperature actuating part is replaced by the gas piston and linear compressor is adopted, which results in low vibration, long life and better durability. It is expected that development of the pulse tube cooler will not only improve our technology to the level of advanced countries, but also enhance the skills in designing and manufacturing of the infrared detector.
염한길(Hankil Yeom),홍용주(Yong-Ju Hong),고준석(Junseok Ko),김효봉(Hyobong Kim),고득용(Deuk-Yong Koh),박성제(Seong-Je Park),인세환(Sehwan In),김혜림(Hye-Rim Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The SFCL (Superconducting Fault Current Limiter) must be cooled to below the critical temperature of HTS(High Temperature Superconductor) modules. In general, they are submerged in sub-cooled liquid nitrogen because of their thermal stability. To cool and maintain the target temperature and pressure the cryostat should be designed well with a cryocooler and a circulation devices. There are two operation modes in SFCL. One is the standby mode, there exist steady heat load due to heat invasion through current lead, heat invasion from surroundings and heat generation by AC loss. Their heat loads are removed by the cryocooler. Another is the quench mode, when the HTS modules are quenched with the event of high current, it instantaneously generates large amount of heat. This heat is removed by the liquid nitrogen’s latent heat of evaporation, so the generated nitrogen gas should be exhausted from the cryostat. In this paper, we designed the cryostat and cooling method for the stable operation of the SFCL. To achieve this objective sizing and structural analysis of the cryostat, and design the cooling method as cool in sub-cooled liquid nitrogen.
〈학술논문〉고온초전도 전력케이블용 극저온냉각시스템 개발현황
염한길(Hankil Yeom),고득용(Deuk-Yong Koh),박성제(Seong-Je Park),홍용주(Yong-Ju Hong),고준석(Junseok Ko),김효봉(Hyobong Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
기존에 진행되고 있는 대표적인 국내외 초전도 전력케이블 개발 및 케이블에 적용된 극저온냉각 시스템에 대한 현황을 소개하였다. 현재 초전도 전력케이블은 1 ㎞ 이상 장선화가 진행됨에 따라 수 십 ㎾ 용량의 냉각시스템을 필요로 하고 있다. 지난 10년간 프론티어사업을 통해 초전도케이블은 선진국과 대등한 수준이거나 일부 앞서가는 분야도 있다. 이제는 극저온 냉동기 등의 핵심부품 국산화 개발을 통해 저렴하고 신뢰성 있는 극저온냉각시스템을 갖춤으로서 초전도케이블시스템이 시장에서 경쟁력을 갖출 수 있는 기반을 마련해야 할 때임을 상기해야 할 것이다. Cryogenic cooling is necessary for HTS power cables to perform their intended function. In the cooling process, sub-cooled liquid nitrogen is circulated by a pump to absorb and dissipate the heat generated in the cable and introduced from outside. For successful cooling, the thermal loads of cable systems and the hydraulic characteristics of the cooling passage of the cable should be well investigated to design the long length cables. The cooling capacity of the cable system is decided by evaluating the thermal load. The pressure drop in the cable is an important design parameter, because the pressure drop decides the length of the cable, size of the coolant circulation pump and circulation pressure, etc. Recently, demonstrative and practical researches of the HTS power cable and the cryogenic system are has been actively going. In this paper, the domestic and international current state of this field is described.
경부하 성능향상을 위한 가스바이패스형 오일쿨러에 관한 연구
염한길(Hankil Yeom),이승우(Seung Woo Lee),하승한(Seung Han Ha) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Oil cooler is a temperature controller using oil. The gas by-pass type can provide both acceptable performance and economy with excellent accuracy of temperature control and an economic price. But this type has a problem in low load state. Because traditional gas by-pass type oil cooler has capillary tube expansion device which is restricted the by-passed hot gas. In this study, we recommend the modified control method that can be applied to the gas by-pass type oil cooler. The capillary tube is replaced by an electronic expansion device. There are two dynamic expansion devices in modified oil cooler. One controls liquid refrigerant at condenser outlet and another controls by-passed hot gas at compressor outlet. This cooler can be adapted to low load state by linked controlling of two electronic expansion devices. In test results, modified oil cooler was more effective than traditional cooler.
고준석(Junseok Ko),염한길(Hankil Yeom),홍용주(Yong-Ju Hong),박성제(Seong-Je Park),김효봉(Hyobong Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
This paper describes experimental investigation on neon refrigeration system. A commercial helium compressor was used for compressing neon gas, because neon is an inert gas like as helium and thus, large amount of compression heat is generated in compression process due to its high specific heat ratio. In this paper, neon refrigeration system is fabricated and tested. In cooling performance test, the effect of radiation shield is investigated. With experimental results, the effectiveness of fabricated heat exchangers is analyzed and discussed. From experimental results, 44.0 K and 58.2 K of the lowest temperature are measured according to existence of radiation shield.
고준석(Junseok Ko),염한길(Hankil Yeom),홍용주(Yong-Ju Hong),박성제(Seong-Je Park),서정균(Jeong-Kyun Seo),김효봉(Hyobong Kim),고득용(Deuk-Yong Koh) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Hydrogen is the most promising energy carrier in near future. Liquid hydrogen has advantages in storage and transportation due to its higher density than gaseous hydrogen. Gaseous hydrogen at atmospheric condition is liquefied through cryogenic liquefaction process. This paper describes design of such cryogenic liquefaction cycles. We designed hydrogen liquefaction cycle on the basis of Linde-Hampson liquefaction system. We selected several different cycles as use of GM cryocooler and pre-cooler with liquid nitrogen. From results of analysis, principal parameters such as yield of liquid hydrogen, liquefaction rate and energy consumption are deeply discussed.